Effects of Dietary Daidzein Supplementation on Reproductive Performance, Immunity, and Antioxidative Capacity of New Zealand White Does

This study was conducted to explore the effects of dietary daidzein (DA) supplementation on reproductive functions in rabbit does. A total of 200 New Zealand White does were randomly assigned to four groups and fed a basal diet with no DA (control, CON) or the basal diet supplemented with 85 (DA85), 170 (DA170), and 340 (DA340) mg DA/kg throughout the gestation. Results showed that DA elevated individual embryo weight at 19 days of gestation. DA supple-mentation at 170 mg/kg also elevated the individual and litter birth weight at parturition (P < 0.05). DA supplementation at 170 and 340 mg/kg elevated the serum concentrations of estrogen and IGF-I at 19 days of gestation (P < 0.05), and elevated the concentrations of leptin and high -density lipoprotein cholesterol (HDL-C) at parturition (P < 0.05). DA increased the serum con-centration of IgG, but decreased the concentrations of tumour necrosis factor-alpha (TNF-alpha) and malonic dialdehyde (MDA) (P < 0.05). DA supplementation at 170 mg/kg increased the serum activities of glutathione peroxidase (GSH-Px) and catalase (CAT) at parturition (P < 0.05). Moreover, DA elevated the expression levels of critical genes related to reproductive functions such as the progesterone receptor (PGR), estrogen receptor-beta (ESRRB), and transforming growth factor-alpha (TGF-alpha) in the uterus (P < 0.05). DA supplementation at a moderate dose (170 mg/kg) also elevated the expression levels of epidermal growth factor receptor (EGFR) and nuclear receptor subfamily 5 group A member 2 (NR5A2) in the placenta (P < 0.05). These results suggested that DA can improve the reproductive performance of does, which was associated with elevated serum hormones, immunity and antioxidant capacity, as well as the expression levels of critical genes related to reproductive functions.